Ballistic resistant pad with metal cord

ABSTRACT

A ballistic resistant pad ( 20 ) for use in protective textile or the like comprises one or more sheets ( 22 ) of high-strength fibers, and a plurality of elongated metal elements ( 24 ). The metal elements ( 24 ) are bonded to at least one of the sheets ( 22 ) so as to give to the pad ( 20 ) a degree of resiliency to come back close to its original form after a local impact.

FIELD OF THE INVENTION

The present invention relates to a ballistic resistant pad for use inprotective textile or the like.

BACKGROUND OF THE INVENTION

With increasing violence in the form of terrorism, protective textilesare becoming more and more important. Protective clothing, whichcombines both a sufficient resistance against impacts caused by bulletsand an acceptable level of comfort for the wearer, are nowadays on themarket.

The required degree of impact resistance is achieved due to therelatively great plastic deformations of high-strength fibers. At thespot of the bullet burst a small crater is created in the sheet formedby the high-strength fibers. Locally the material of the high-strengthfibers is contracted and shrinks. The result is that after the bulletimpact, the sheet occupies a decreased surface area and, as aconsequence, protects a decreased surface area. A number of consecutivebullets may result in a substantial surface area becoming unprotected bythe sheet.

SUMMARY OF THE INVENTION

It is an object of the present invention to avoid the drawbacks of theprior art.

It is another object of the present invention to increase the degree ofsecurity of protective clothing.

It is still another object of the present invention to give adequateprotection even after one or more bullet impacts.

According to the present invention, there is provided a ballisticresistant pad for use in protective textile or the like, e.g. inprotective clothing. The pad comprises one or more sheets ofhigh-strength fibers and a plurality of elongated metal elements. Theelongated metal elements are attached to at least one of the sheets in away to give to the pad a degree of resiliency to come back close to itsoriginal form after a local impact.

The elongated metal elements may be metal wires or metal cords.Preference is given to metal cords, because of their flexibility andresulting increased comfort for the user in comparison with metal wiresof the same cross-section. The metal cords are preferably steel cords.

In order to be effective the metal elements are spread over the surfaceof the sheet of high-strength fibers.

The elongated metal elements may be present in the ballistic resistantpad in the form of individual elongated metal elements or, preferably,may be present in the form of a fabric of woven or knitted elongatedmetal elements.

In order to provide the ballistic resistant pad with sufficientresiliency and integrity upon bullet impact, the elongated metalelements are preferably attached to all present sheets of high-strengthfibers.

The attachment of the elongated metal elements to the sheets ofhigh-strength fibers may be done by means of an adhesive or by means ofa thermoplastic film. Preferably, however, the elongated metal elementsare stitched to the sheets of high-strength fibers.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described into more detail with reference tothe accompanying drawings wherein

FIG. 1 illustrates the functioning of a prior art embodiment;

FIG. 2 and FIG. 3 illustrate each an embodiment according to theinvention with individual steel cords;

FIG. 4 and FIG. 5 show each an embodiment according to the inventionwith steel cord fabrics.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 illustrates the phenomenon of a bullet impact occurring on aprior art ballistic resistant pad 10. The ballistic resistant pad 10comprises one or more sheets 12 of synthetic high-strength fibers. Abullet creates a small crater 14. In the neighborhood of this crater thesheet material is shrinked and contracted to a degree that the sheet nowhas as borders 16 whereas the original borders 18—shown in dashedlines—covered a substantially larger area. Other subsequent bulletimpacts on other locations will also create craters, which will resultin a further decrease of the protected surface.

FIG. 2 shows a first embodiment of the invention. The ballisticresistant pad 20 comprises one or more sheets 22 of high-strengthfibers. Useful high-strength fibers for the sheets of aballistic-resistant pad are aramid fibers, para-aramid fibers,high-density high-molecular weight polyethylene fibers,poly(p-phenylene-2,6-benzobisoxazole) fibers (PBO fibers),polybenzimidazole fibers (PBI fibers) or any combination or mixturehereof.

Individual lengths of steel cords 24 are attached by means of stitchesto the sheets 22. The steel cord lengths 24 form a particular pattern onthe sheets 22 so that a large area is covered. Preferably, triangularstructures are formed because of their inherent stability. Althoughflexible from a comfort point of view, the steel cords 24 are stiffer incompression than the high-strength synthetic fibers and give aresiliency to the sheet 22 so that this sheet 22 is able to restraindeformation in the plane and recover from a bullet impact and can comeback close to its original form after a bullet impact.

FIG. 3 shows a second embodiment of the invention. The ballisticresistant pad 20 has now another pattern of individual lengths of steelcord 24.

The present invention is not limited to a particular type of elongatedmetal elements. Metal wires and metal yarns are suitable. However,because of flexibility and comfort reasons coupled with safety reasonspreference is given to metal multi-strand metal cords with relativelythin filaments, i.e. filaments with a diameter ranging from 0.03 mm to0.35 mm., e.g. from 0.05 mm to 0.32 mm.

Multi-strand metal cords are usually of the m×n-type, where m is thenumber of strands and n is the number of filaments within one strand.Examples of multi-strand cords are

-   -   3×3    -   7×3    -   7×4    -   4×7    -   3+5×7    -   7×7.

Other cord types or not excluded. These other cord types may be offollowing general structure:

-   -   l+m (+n): l core filaments, a layer of m filaments and, possibly        a layer of n filaments    -   n×1: n filaments twisted together, n ranging from 2 to 6, hence        2×1, 3×1, 4×1, 5×1, 6×1; these n×1 cords may be of the closed        type, i.e. the cross-section has a closed configuration        preferably, however, these n×1 cords are of the open type,        designated as OC (“open cord”), i.e. the cross-section is of the        open type, i.e. not all neighboring filaments touch or contact        each other    -   m+n: m filaments in parallel, surrounded by n filaments twisted        around each other and around the m filaments    -   1×n CC: compact cord with n filaments all twisted with the same        twisting step in the same twisting direction.

The metal cords may be made starting from following steel composition: acarbon content higher than 0.60%, a manganese content ranging between0.30% and 0.80%, a silicon content ranging from 0.10% to 0.40% andpreferably maximum sulphur and maximum phosphorous contents of 0.03%.Lower carbon contents, e.g. below 0.40% are not excluded either.

The invention is neither limited to a particular type of coating on themetal cords. This coating can be a metal coating. However, in case thestab-resistant insert is used in a protective textile, which needs to bewashed or cleaned, preference is also given to metal cords out ofstainless steel or to steel cords being covered with acorrosion-resistant coating such as zinc or a zinc aluminum alloy (from2% to 9% aluminum).

Above the metal coating, or above the steel, a synthetic coating may beprovided. The synthetic coating provides some additional corrosionresistance. The presence of a synthetic coating increases the stiffnessof the cord. The synthetic coating may be a polyester, a polyamide, apolyvinylchloride, and the like.

The invention is suitable for all common and available final tensilestrengths from 1500 MPa to about 3500 MPa and more.

FIG. 4 shows a third embodiment of the invention. The ballisticresistant pad 20 has one or more sheets 22 of high-strength syntheticfibers. A fabric 26 of woven steel cords 28, 30 of about the same formas the sheets 22 is stitched at various spots to the sheet 22 andprovides for a complete covering of the sheet. The fabric 26 is a wovenstructure where both the weft 28 and the warp 30 are formed by steelcords.

FIG. 5 shows a fourth embodiment of the invention. Here again theballistic resistant pad 20 may have one or more sheets 22 of appropriatehigh-strength synthetic fibers. A first fabric 32 with steel cords 34 inwarp and synthetic yarns (not shown) in weft is stitched to the sheets22. A second fabric 36 with steel cords 38 in warp and synthetic yarns(not shown) in weft is stitched through the first fabric 32 to thesheets 22. The direction of the steel cords 34 in the first fabric 32 isdifferent from the direction of the steel cords 38 in the second fabric36.

If a fabric of steel cords is used instead of individual steel cordelements, the present invention is not limited to the type of fabric.

In one embodiment, steel cords may form the warp whereas synthetic yarnssuch as aramide may form the weft. A nylon filament, such as nylon940/2/2 binds the warp to the weft.

In a second embodiment of steel cord fabric, steel cords form the weftwhereas synthetic yarns form the warp.

In a third embodiment of a steel cord fabric, steel cords both form theweft and the warp. In a first sub-embodiment, the weft and the warp runstraight and are be bound together by means of a synthetic yarn. In asecond sub-embodiment, the weft and the warp are interwoven and do notneed an additional synthetic yarn for binding.

In a fourth embodiment of a steel cord fabric, steel cords form the weftand synthetic filaments form the warp in an alternating zigzag way: afirst synthetic filament goes over and under and over the steel cords asecond nylon filament goes under and over and under the steel cords,etc. . . .

As a matter of example, a woven fabric is obtained with a 3×0.30 OC(open cord) as weft and warp and with sizes of mesh 4×4 mm or 3×3 mm.Such a woven fabric has the advantage of being light and of providing ahigh degree of stiffness in a direction perpendicular to the plane ofthe fabric.

The ballistic pad may be inserted in a cover that is impermeable tomoisture. Such a cover can be made out of a fabric of GORETEX® fibers.

1. A ballistic resistant pad for use in protective textile or the like,said pad comprising one or more sheets of high-strength fibers, and aplurality of elongated metal elements, said metal elements beingattached to at least one of said sheets so as to give to said pad adegree of resiliency to come back close to its original form after alocal impact.
 2. A pad according to claim 1, wherein said elongatedmetal elements are steel cords.
 3. A pad according to claim 1, whereinsaid elongated metal elements are spread over the surface of the sheet.4. A pad according to claim 1, wherein said elongated metal elements arepresent in said pad in the form of a fabric of woven or knitted metalelements.
 5. A pad according to claim 1, wherein said metal elements areattached to all of said sheets.
 6. A pad according to claim 1, whereinsaid metal elements are attached to at least one of said sheets by meansof stitching.
 7. A pad according to claim 2, wherein said elongatedmetal elements are spread over the surface of the sheet.
 8. A padaccording to claim 2, wherein said elongated metal elements are presentin said pad in the form of a fabric of woven or knitted metal elements.9. A pad according to claim 3, wherein said elongated metal elements arepresent in said pad in the form of a fabric of woven or knitted metalelements.
 10. A pad according to claim 2, wherein said metal elementsare attached to all of said sheets.
 11. A pad according to claim 3,wherein said metal elements are attached to all of said sheets.
 12. Apad according to claim 4, wherein said metal elements are attached toall of said sheets.
 13. A pad according to claim 2, wherein said metalelements are attached to at least one of said sheets by means ofstitching.
 14. A pad according to claim 3, wherein said metal elementsare attached to at least one of said sheets by means of stitching.
 15. Apad according to claim 4, wherein said metal elements are attached to atleast one of said sheets by means of stitching.
 16. A pad according toclaim 5, wherein said metal elements are attached to at least one ofsaid sheets by means of stitching.